1. Field of the Invention
This invention relates to an arrangement for measuring the humidity in ovens in general, and in particular in food-cooking ovens, so as to regulate the degree of humidity to a pre-determined level during food cooking processes performed in the oven.
2. Description of Related Art
Food-cooking ovens are known from the prior art to be constituted substantially by a box-like outer casing delimiting an inner cooking cavity in which food to be cooked is arranged. A forced circulation of hot air is brought about in said cooking cavity through a gas-fuelled or electric heat generator and a fan. Some ovens are also provided with a steam generator for steam cooking.
Such ovens are equipped with appropriate thermostatic control systems to regulate the food cooking temperature. Associated temperature selector means are set at the desired temperature value before starting any cooking process to be performed in accordance with the kind and amount of food to be cooked. The thermostatic temperature control systems equipping said ovens operate to keep the food cooking temperature within pre-defined limits inside the cooking cavity, in general, by energizing and de-energizing the heat generator and/or the steam generator, and the air-moving fan, so as to vary in an appropriate way the flow of air circulating through the cooking cavity.
These ovens, however, are not provided with any arrangement for regulating the humidity of the air inside the cooking cavity, a factor that, in conjunction with the temperature, definitely affects the quality of the cooking results and the taste and flavor of the food items being cooked. Humidity is variable depending on various parameters of the cooking process such as the cooking temperature, the kind and the amount of the food to be cooked, the air replacement rate in the cooking cavity, etc. Thus, these appliances do not enable optimal food cooking results to be achieved.
Humidity measurement devices are known in connection with applications of a different kind. These are generally constituted by semiconductor sensing means which are arranged in the moist environment to be controlled and are connected with electrical bridge-type measurement circuits that are adapted to detect the corresponding electric quantities generated by said sensing means and to automatically convert them into corresponding humidity levels prevailing in said moist environment.
Other humidity measuring devices are constituted by elements measuring the concentration of oxygen in gas mixtures, such as for instance in the case of zirconium oxide cells, according to known principles of operation.
However, all of these humidity measurement devices, while ensuring correct and accurate measurements, are on the other hand scarcely suited to measure the humidity under typical food cooking temperature conditions, which usually range from 100.degree. C. through to 250.degree. C. according to the type and the amount of food to be cooked. Said devices would either become damaged, and therefore would be prevented from performing their function, or they would not be able to ensure an adequately reliable operation, since their sensing elements would be subject to soiling.